Sheath blight of rice

causal organism, history, distribution,symptoms,life cycle,Integrated Disease Management

1. SHEATH BLIGHT OF RICE COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), ViaVaigai Dam, Theni-625 562 STUDENT Miss. ABIRAMI.C ID. No. 2015021003 COURSE TEACHER Dr. PARTHASARATHY S Asst. Professor (Plant Pathology)

2. RICE SHEATH BLIGHT / BANDED LEAF BLIGHT CAUSAL ORGANISM Anamorph - Rhizactonia solani ( Julius Kuhn) Telomorph - Thanatephororus cucumeris ( A.B Frank.Donk )

3. HISTORY Disease was first recorded in Japan( Miyake, 1910 ). In India, the disease was first reported from Gurudasar , Punjab ( Paracer and Chahal , 1963 ). Later it was first reported from Uttar Pradesh ( Kohli , 1996 ). Estimates of yield reduction due to sheath blight have been reported ranging from 5.2 to 6.9 % (Hori 1969; Kannaiyan and Prasad 1978; Naidu 1992 ).

4. Rice sheath blight / Banded leaf blight Vernacular name – Snake skin disease When several such lesions are developed continuously on a greenish tissue, it almost looks like a snake skin from a distance and so it is called by the farmers as snake skin disease. Local Kannada name – Yele Kavachada Machee Roga

5. SYSTEMATIC POSITION Domain - Eukarya Kingdom - Fungi Phylum - Basidiomycota Class - Agariomycetes Order - Cantharellales Family - Certobasidiaceae Genus - Thanatephorus Species - T . cucumeris

6. ECONOMIC IMPORTANCE In Japan, the disease caused a yield loss of as high as 20% and affected about 12,000 – 1,90,000 hectares. A yield loss of 25% was reported if the flag leaves are infected. In the United States, a yield loss of 50% was reported when susceptible cultivars were planted. Studies at IRRI showed that sheath blight causes a yield loss of 6% in tropical Asia.

7. OCCURRENCE IN WORLD United states of America Tropical Asia Australia Phillipines

8. OCCURRENCE IN INDIA The sheath blight appeared in moderate to severe intensity in a few states like Andra Pradesh, Kerala, Orissa, West Bengal.

9. SYMPTOMS Symptoms appear from tillering to heading stage. Lesions appear on sheaths on lower leaves near the water line. Lesions appear on leaf collar oval to elliptical greenish grey water soaked spots ¼ inch wide, ½ to 1 ¼ inch long. During favourable condition, lesions enlarge forming irregular shaped lesions with greyish white centres with dark brown borders.

10. The infection extends to the inner sheaths resulting in death of the inner sheath resulting in death of the entire plant. Five to six week old leaf sheaths are highly susceptible. The presence of several large lesions on leaf sheath usually cause death of the whole leaf and in severe cases all the leaves of a plant may be blighted.

11. SYMPTOMS © agritech.tnau.ac.in ©agritech.tnau.ac.in

12. FAVOURABLE CONDITIONS High infection at 100% RH. High temperature (28 – 32◦ C). Frequent rainfall favours disease development. High dose of nitrogen. Close planting favours pathogen attack. High seed rate.

13. MODE OF INFECTION Primary spread of disease - all grasses, broad leaved weeds grown on rice bunds produce similar symptoms and producing sclerotial bodies. Sclerotial bodies fall in paddy water and initate infection on rice crop. Secondary spread of infection - Seed borne, wind borne and water borne disease.

14. PATHOGEN CHARACTERS Fungus produce usually long cells of septate mycelium which are hyaline when young, yellowish brown spherical when old. Individual sclerotia are 1-3mm in diameter. Sclerotia are formed on or near the spots and can be easily detached from the plant. Pathogen survive as sclerotia in dry soil for 20 months but for 5 to 8 months in moist soil.

15. © agritech.tnau.ac.in LIFE CYCLE LILLKDJDNSDN

16. © https://www.slideshare.net/FOODCROPS/yongi-screening-for-resistance-to-rice-disease

17. MYCELIUM OF Rhizoctonia solani BASIDIOSPORE OF Rhizoctonia solani © https:ww.cals.ncsc.edu

18. INTEGRATED DISEASE MANAGEMENT CULTURAL METHODS Avoid closer spacing. Use moderately resistant varieties like Swarauhan , Pankaj , Mansarovar and Radha etc., Split application of nitrogen ferilizer . Deep ploughing in summer. Burning of stubbles. Eliminate weed host.

19. CHEMICAL METHODS Seed treatment with Carbendazim 2 g/ kg of seeds. Hexaconazole 75% WP @ 1 00 mg / litre 1 st spray at the time of disease appearance and 2 nd spray 15 days after first spraying. Spraying of Chlorothalanil 1 Kg or Edifenphos 1 lit/ ha. Spraying of Carbendazim ( 1g /lit), Propiconzole (1 ml/lit)may be applied. Spray Validamycin 3 L @ 2.5 ml / litre of water or Thifluzamide 24 EC@ 1 ml/lit of water.

20. BIOLOGICAL METHODS A ntogonist micro- organisms fluorescent bacteria were isolated that showed high level of antogonism against sheath blight pathogens. Foliar spray with Pseudomonas fluorescens TNAU P.f 1 liquid formulation @ 5 ml / ha. Seed treatment with P. fluorescens @ 10 g/kg of seed.

21. Soil application of Pseudomonas fluorescens @ 2.5 Kg / ha was mixed with 50 kg of FYM / 50 kg of fine Sand. Seedling dip P .fluorescens @ 2.5 kg product / ha in 100 lit of water for 30 minutes. In Rajashahi , press – mud, saw dust and rice bran reduced disease severity.

22. REFERENCES www.knowledgebank.irri.org agropedia.iitk.ac.in agritec.tnau.ac.in